Mixtures of 5-silamidazolidones-(2) which contain isocyanate groups and urethanes

ABSTRACT

MIXTURES OF URETHANES AND 5-SILISMIFSZOLIDONES-(2) WHICH CONTAINISOCYANATE GROUPS AND A PROCESS FOR THE PREPARATION OF SAID MIXTURES ARE DISCLOSED. THE COMPOSITIONS OF THE INVENTION ARE EMINENTLY SUITED AS BONDING INTERLAYERS FOR SILICEOUS OR METALLIC SURFACES WHICH ARE TO BE COATED WITH SYNTHETIC RESINS OR ELASTOMERS.

United States Patent 3,793,253 MIXTURES 0F S-SILAIMIDAZOLIDONES-(Z)WHICH CONTAIN ISOCYANATE GROUPS AND URETHANES Bernd Quiring and KunoWagner, Leverkusen, Ingrid Irene Klfirchen Giilitz, Cologne, and WalterNoll, Opladen, Germany, assignors to Bayer Aktiengesellschaft,Leverkusen, Germany No Drawing. Filed Aug. 1, 1972, Ser. No. 277,000Claims priority, application Germany, Aug. 4, 1971, P 21 38 943.5 Int.Cl. C08g 22/22; C09j 3/00 US. Cl. 26077.5 AT 2 Claims ABSTRACT OF THEDISCLOSURE Mixtures of urethanes and -silaimidazolidones-(2) whichcontain isocyan-ate groups and a process for the preparation of saidmixtures are disclosed. The compositions of the invention are eminentlysuited as bonding interlayers for siliceous or metallic surfaces whichare to be coated with synthetic resins or elastomers.

This invention provides new systems which are eminently suitable for useas interlayers for bonding siliceous or metallic surfaces to syntheticresins.

This invention relates to mixtures comprising:

(a) 5 silairnidazolidones (2) containing isocyanate groups, having thefollowing formula:

wherein R and R are the same or different and are optionallyhalo-substituted or cyano-substituted C -C alkyl, and C -C alkoxyradicals which may be substituted by halogen or cyano-groups or R and Rtaken together represent a bis-oxy alkylene group containing l-3 carbonatoms,

R is hydrogen, an aliphatic or cycloaliphatic hydrocarbon radicalcontaining up to 15 carbon atoms which may be olefinically unsaturatedor an aryl radical containing up to carbon atoms; and

R is a divalent aliphatic, cycloaliphatic, araliphatic or aromaticradical containing up to carbon atoms which may contain hetero atomssuch as oxygen, nitrogen or sulphur or ester groups with (b) urethanes0f the general formula:

R OCONH-R -(NCO) in which m is 0 or 1; R is C to C alkyl; and R is aradical R when m=1, and when m=0, it represents a radical of thefollowing general formula:

wherein R R R and R are as defined hereinabove.

This invention also relates to a process for the preparation of mixturesof (a) 5-silaimidazolidones-(2) contain- 3,793,253 Patented Feb. 19,1974 ice ing isocyanate groups and (b) urethanes wherein an aminomethylalkoxysilane having the following formula:

I R5 wherein R R R and R have the meanings indicated above is reactedwith a diisocyanate of the following formula:

OCNR NCO 'wherein R, has the meaning given above, at temperatures offrom about 20 C. to about C. in such proportions that the reactionmixture contains at least one mol of diisocyanate per gram equivalent ofprimary or secondary amino groups.

The starting materials for the process according to the invention may beany aminomethyl alkoxysilanes of the given formula.

It is preferred, however, to use compounds wherein R is a radicalcontaining up to 6 carbon atoms, some examples of which areN-cyclohexylaminomethyl -ethoxy-dimethylsilane,

N-cyclohexylaminomethyl) -diethoxy-methylsilane,

N-phenyl-(aminomethyl)-triethoxysilane,

N-isobutylaminomethyl) -triisopropoxysilane,

N-cyclohexyl- (aminomethyl) -triethoxysilane,

N-cyclohexylaminomethyl) -diethoxy-tert.-butyloxysilane,

N-cyclohexyl- (aminomethyl -ethoxy-ethylene dioxysilane,

N-vinyl- (aminomethyl -triethoxysilane,

aminomethyl-trimethoxysilane, and the like.

Aminomethyl-alkoxysilanes which are especially preferred areN-cyclohexyl- (aminomethyl) -ethoxy-dimethylsilane,

N-cyclohexylaminomethyl -diethoxy-methylsilane,

N-phenyl- (aminomethyl )-triethoxysil ane,

N-isobutyl- (aminomethyl -triisopropoxysilane,

N-cyclohexyl- (aminomethyl -triethoxysilane andN-cyclohexyl-(aminomethyl)-ethoxy-ethylene dioxysilane.

Any diisocyanates of the given formula may be used for the processaccording to the invention, some suitable examples of which are:

O diphenyl-4,4-diisocyanate;

di- (4-isocyanatophenyl) -methane;

naphthylene-1,5-diisocyanate; di-(4-isocyanatophenyl)-oxide;di-(4-isocyanatophenyl)-sulphide;2-trichloromethyl-4,6-diisocyanato-s-triazine; and the like.

Especially preferred diisocyanates are 1,6-hexamethylene diisocyanate;trimethyl-l,6-diisocayanatohexane; 1,4-diisocyanatocyclohexane;dicyclohexylmethane-4,4'-diisocyanate;

p and m-xylylene diisocyanate;

methyl diisocyanatocyclohexane;3-isocyanatomethyl-3,5,S-trimethylcyclohex'yl isocyanate;a,e-diisocyanato caproic acid methyl ester, and

tolylene diisocyanate.

The above mentioned aminomethyl-alkoxysilancs and diisocyanates may beused alone or as respective mixtures in the preparation of the mixturesaccording to the invention. The aminomethyl alkoxysilanes may alsocontain, for example, small quantities of silicon-free amines, and theisocayanates used may contain solvents.

The aminomethyl silanes containing alkoxy groups and the diisocyanatesare reacted together at temperatures of from about -20 C. to about +150C., preferably from about C. to about 120 C., such that an excess ofdiisocyanate is always present. The reaction is preferably carried outwith the exclusion of moisture. For example, the liquidaminoalkyl-alkoxysilane, if desired, in a solvent which is inert to bothreactants, such as for example, benzene, toluene, xylene, chlorobenzene,o-dichlorobenzene and the like, is added dropwise with stirring to thediisocyanate which may, if desired, be preheated and the reactionmixture is kept at the desired temperature by controlling the rate ofaddition of amine. At least 1 mol of diisocyanate but preferably morethan 2 mols, i.e., up to about 20 mols are used for 1 mol of aminogroups.

If desired, the reaction may be carried out in the presence of one ormore catalysts, preferably tertiary amines such as, for example,triethylamine, pyridine, methyl pyridine, N,N dimethyl benzylamine, N,Ndimethyl aminocyclohexane, N,N'-dimethyl piperazine, N,N'-endoethylenepiperazine and the like; amidines such as, for example,1,5-diazabicyclo-(O,4,5)-undecene-(5) and the like; or metal salts suchas, for example, iron (HI) chloride, zinc chloride, tin-(II)-2ethylcaproate, dibutyl tin (IV)-dilaurate, molybdenum glyeolate, zinc-Z-ethylcaproate and the like.

If the reaction is carried out at temperatures below 60 C., it generallytakes several hours to several days before formation of thesilaimidazolidone ring is completed.

To remove excess diisocyanate, the reaction mixtures are advantageouslysubjected to continuous flow or thin layer distillation. Continuousdistillation of unreacted starting material is generally carried out atfrom about 80 C. to about 250 C., preferably from about 90 C. to about210 C., at reduced pressure, preferably at less than about 50 mm. Hg.The conventional continuous flow or falling film evaporators whose modeof operation is described, for example, in German patent specificationNo. 1,090,196 may be used.

Products containing double bonds which are capable of radicalpolymerization may be treated with suitable polymerization inhibitors,such as for example, hydroquinone and the like before the thin layerdistillation is carried out.

It is sometimes advisable to dissolve the mixture of reaction productsand excess diisocyanate in a suitable solvent such as, for example,xylene, chlorobenzene, o-dichlorobenzene and the like which acts asvehicle for the diisocyanate in thin layer or continuous flowdistillation.

Thin layer distillation may be repeated several times until thedistillation residue is substantially free of monomeric diisocyanate.

In cases where the presence of unreacted diisocyanate would notinterfere with subsequent intended use of the products, thin layer orcontinuous flow distillation may be carried out in such a manner that acertain amount of the starting material which has been used in excess isleft in the reaction mixture.

If desired, unreacted diisocyanate may also be removed by extractionwith suitable solvents such as, for example, c'yclohexane, petroleumether, cleaning petrol or the like.

The mixtures of substances according to the invention are formed fromaminomethyl alkoxysilanes and diisocyanates in accordance with thefollowing reaction mechanrsm:

compound:

Rz CH2 Si N rift-(1:0

If the ring closing reaction is completed in the falling filmevaporator, it is possible under certain conditions, especially if asecondary or tertiary alcohol is split off in the process, partly todistill this alcohol from the reaction mixture instead of reacting itwith an isocyanate group.

The mixtures according to the invention obtained by the precess of theinvention are mainly 3-component mixtures because Compound III which isformed as intermediate product reacts not only with excess diisocyanateII (R (NCO) R =lR m=1) but also with itself:

'5 The mixtures according to the invention are thus composed ofCompounds IV, VI andVII.

If only one mol of dii socyanate II is used per mol ofaminomethyl-alkoxysilane I, the product obtained by the processaccording to the invention consists almost exclusively of VII. The useof a large excess of diisocyanate results in the preferential formationof mixtures of IV and VI and only a small proportion of VII.

The mixtures according to the invention generally contain about 1 mol ofCompound IV, from 0 to about 1 mol of Compound VI and from 0 to about 10mols, preferably from about 0.01 to about 5 mols of Compound VII.

Although it is already known (see, for example, DOS

No. 1,954,447) that aminomethybalkoxysilanes react with monoisocyanatesto produce substituted ureas which split off alcohol when heated to form5-silaimidazolidone- (2) rings, it was nevertheless surprising that atthe high temperatures encountered during thin layer distillation thesimultaneous. presence of .free isocyanate groups and groups which arereactive with isocyanate groups, for example, groups containingN-I-I-bonds, do not lead to further addition reactions. Since the ringclosing reaction in the process according to the invention proceeds atcomparatively low temperatures, it is all the more surprising that evenwhen R and/ or R are alkoxy groups no further intermolecularcondensation takes place at the high temperatures of thin layerdistillation and with the large excess of isocyanate groups presentwhich act as alcohol acceptors. Both these reactions would lead to anincrease in molecular weight, severe reduction in the NCO content andpossibly to cross-linking reactions. Instead, the products obtained bythe process have a high NCO-content and an excellent adhesive powerwhich enables them to be bonded to various materials. The proportion ofurethane groups to silicon atoms is in no case greater than 1.

The following are given as examples of S-silaimidazolidones-( 2) IVwhich are obtained in the mixtures according to the invention inadmixture with urethanes VI from the diisocyanate (OCN-R NOO) II used asstarting material and the alcohol (R OH) splitotf on ring closure andwith the corresponding 5 silaimidazolidones-(2) VII which containurethane groups:

TABLEContinued fi-silamidazolidones-(Z) Prepared from- The Si-N-bonds ofthe S-silaimidazolidone-(Z) rnigs can easily be split by hydrolysis andalcoholysis to form substituted ureas.

If the product mixtures according to the invention are prepared frompure starting materials they are stable 75 if stored with exclusion ofmoisture. They are odorless and are generally in the form of highlyfluid to moderately viscous liquids which have optimum solubility andworking-up properties.

The isocyanate groups of the products according to the invention may bereacted in known manner with the usual blocking agents such as thosedescribed e.g. by -E. Miiller in Houben-Weyl Methoden der organischenChemie XIV, 2, Stuttgart 1963, p. 61 et seq. Suitable blocking agentsare, for example, e-caprolactam, phenol, tert. butanol, butanone-Z-oximeand the like. The same compounds which are capable of splitting ofiisocyanate are also obtained when diisocyanate which has been blocked ononly one isocyanate group is reacted with the aminomethyl-alkoxysilaneand ring closure is carried out under conditions which favor thesplitting off of alcohol, for example, at elevated temperature and undervacuum.

The products may be used as bonding interlayers applied to siliceous ormetallic surfaces which are to be coated with synthetic resins orelastomers.

The invention is further described in the following examples, wherein,unless otherwise indicated, the parts and percentages are by weight.

I EXAMPLE 1 H5020 CH2 HsCz-O.

2M Hz)eNC O NCO Molar ratio approximately 1:1:0.7.

About 840 parts of hexamethylene diisocyanate are heated to from about85 C. to about 90 C. with exclusion of moisture in a 1-literthree-necked flask equipped with stirrer, reflux condenser, droppingfunnel and thermometer. About 139 parts ofN-cyclohexyl-(aminomethyl)-triethoxysilane are added dropwise at thistemperature in the course of about 3 hours and stirring is thencontinued for about another 60 minutes. After cooling, the reactionproduct is subjected three times to thin layer distillation in a vacuumthin layer evaporator at from about 120 C. to about 125 C. and about 0.1mm. Hg. A clear, yellow liquid of low viscosity having an NCO- contentof about 9.6% and a silicon content of about 5.25% is' obtained.

An. approximately 5% solution of the product mixture in xylene isapplied as a thinlayer to a degreased glass plate and left to dry. It isthen coated with a 2-com- "ponent "lacquer of commercialtriisocyanatohexylbiuret and a polyester of phthalic acid andtrimethylolpropane having an OH-content of about 8% which is catalyzedwith about 0.2% zinc-2-ethyl caproate on solid carrier. For comparison,the same lacquer is applied in the same thickness to a degreased glassplate. The lacquered plates are dried in air for about 5 days and thenstored in .distilled water for about 3 days. The coated film can ,thenvery easily be. stripped intact from the untreatedplate but the filmapplied to the plate which had been pretreated with the product mixturecan only be scratched oif in small chips with a sharp knife.

Molar ratio approximately l:0.3:0.4.

About 139 parts of N-cyclohexyl-(aminomethyl)-triethoxysilane are addeddropwise to about 840 parts of hexamethylene diisocyanate at atemperature of about 45 C. in the course of about 2 hours in theapparatus described in Example 1. The reaction mixture is left to coolto room temperature and the mixture of products is purified by thinlayer distillation at about C./ 0.05 mm. Hg. A clear, yellow liquid oflow viscosity containing about 5.89% Si, about 8.6% NCO and about 26.0%OC H is obtained.

EXAMPLE 3 HsCzO-CO N 11111 H5010 I J;

2)o (Gibb-NCO NCO H OzO C 2 H2) r-NH-C OO-CH5 Molar ratio approximately1:0.0410.8.

About 137.5 parts of N-cyclohexyl-(aminomethyD- triethoxysilane areadded dropwise to about 588 parts of hexamethylene diisocyanate betweenabout 0 C. and about 5 C. in the course of about 100 minutes in theapparatus described in Example 1. As soon as this operation iscompleted, the product mixture is distilled four times by thin layerdistillation at about C./ 0.07 mm. Hg, the mixture being introduced intothe thin layer evaporator from a dropping funnel cooled to about 12 C.to about 14 C. and the distillation sump being cooled to about 0 C. Aclear, yellow liquid of low viscosity is obtained which contains about.5.8% NCO and about 6.7% Si.

Molar ratio approximately 1:1:1.6.

About 100 parts of N-cyclohexyl-(aminomethyl)-triethoxysilane are addeddropwise to about 183 parts of hexamethylene diisocyanate in the courseof about 115 minutes at about C. in the apparatus described inExample 1. When this operation is complete, about 100 parts areimmediately removed by thin layer distillation at about 120 C./0.06 mm.Hg and the residue is then stirred for about 2 hours at about 120 C. andsubjected to thin layer distillation at about 125 C./0.06 mm. Hg untilthe NCO-content is constant. A clear, yellow liquid containing about6.7% NCO, about 5.4% silicon and having a viscosity of about 1030 cp. at20 C. is obtained.

EXAMPLE 5 H5Cz0\ /Cg2 /T C 5 20 N l CH3 CH3 H5010 CHI CH3 CHa EMMPLE 6H5CzO\ /Cgz /S1 N- H 5 2 I IE-NCO About 82.5 parts ofN-cyclohexyl-(aminomethyl)-triethoxysilane are added dropwise to about400 parts of a commercial mixture of about 2 parts of 2,2,4- and about 1part of 2,4,4-trimethylhexamethylene diisocyanate at room temperature inthe course of about 8 hours with the exclusion of moisture in theapparatus described in Example 1. Stirring is then continued for about 1hour and the mixture is left to stand for about 6 days (until ringclosure is completed). The product is then purified by thin layerdistillation at about 125 C. and about 0.05 mm. Hg.

A yellow, clear liquid of low viscosity having an NCO- content of about8.35% is obtained.

EXAMPLE 7 sCzO 2 H5020 I l/H:

Hz-NOO HaCzO CHz-NCO Molar ratio approximately 1:1:0.4.

The procedure is the same as in Example 6, but using about 480 parts ofm-xylylene diisocyanate and about parts ofN-cyclohexylaminomethylene-triethoxysilane. A clear, yellow liquid ofmedium viscosity having an NCO- content of about 9.5% is obtained.

HaCgO about 172 parts of hexamethylene diisocyanate and about 39.4 partsof N-phenyl-(aminomethyl)-triethoxysilane. A clear, yellow liquid of lowviscosity having an NCO-content of about 8.0% and a silicon content ofabout 5.5% is obtained.

13 EXAMPLE9 T' 3 CE: a Mom V /CHO on, N CH; 11.94v on, Si N-om-bn om bel v /CE0 :0 Ha Nrr CH1 Ha (I: (Hrh H:)a-NCO NCO CHO\ CH CH i I 3 on SiN-om-ofi CH: \CH

cn-wo' N- =0 cm CH: H2) e-NH-C 0-0-05 Molar ratio approximatelyl:0.15:0.6.

The procedure is the same as in Example 1, but using about 135 partsof-hexamethylene diisocyanate and about 33.3 parts of Nisobutyl-(aminomethyl)-triisopr0poxysilane. A yellow, clear liquid oflow viscosity having an NCO-content of about 7.8% is obtained.

EXAMPLE 10 Molar ratio approximately '1 120.5."

The procedure-is the same'as in Examplel, but using about 365 parts oftolylene-2,4 diisocyanate and about82 parts ofN-cyclohexyl-(aminomethyl)-triethoxysilane. A yellow, resinous producthaying an NCO-content of about 10.4% is obtained after thin 130 C./0.05mm. Hg.

EXAMPLE 1 1 layer distillation at, about 1 mclo oo NH Molar ratioapproximately 111:0.7.

The procedure is the same as in Example 1, but using about 510 parts ofbis-(4-is0cyanatocyclohexyl)-methane and about 75 parts ofN-cyclohexyl-(aminomethyD-triethoxysilane. A yellow, clear liquid of,low viscosity having an NCO-content of about 7.0% is obtained after thinlayer distillation at about 150 C. and 210 C. and 0.05 mm. Hg.

EXAMPLE 12 crr f r, user-co S1 N 11111 cm; L (o t),

oH-Noo (CHz)4--CH-COOCH3 A l. 0 N00 I 0 (EH; H3O jig:

Molar ratio approximately 1:1:0.3.

The procedure is the same as in Example 1, but using about 742 parts ofa,e-diisocyanato caproic acid methyl ester and about 107.5 Y parts of Ncyclohexyl (aminomethyl)-eth0xy-dimethylsilane, and a yellow, clearliquid of low viscosity having an NCO-content of about 10.0% and asilicon content of about 4.8% is obtained after thin layer distillationat about 145 C. and 0.05 mm. Hg.

EXAMPLE 13 Molar ratio approximately 1:1:0.7.

About 54 parts of caprolactam are dissolved at room temperature withexclusion of moisture in about 200 parts of the product mixture obtainedaccording to Example 1, using a (LS-liter three-necked flask equippedwith stirrer, reflux cooler, thermometer and tube for passing nitrogenover the mixture. The mixture is then stirred at from about C. for about2 /2 hours. A clear, yellow liquid which is free from NCO is obtained.

15 EXAMPLE 14 H30 CH Molar ratio approximately 1:1:0.6.

About 75 parts of N cyclohexyl (aminomethyl)-diethoxymethylsilane areadded dropwise to about 360 parts of hexamethylene diisocyanate in thecourse of about 2 hours at about 100 C. in the apparatus described inExample 1 and the reaction mixture is then stirred at the sametemperature for about 30 minutes. After thin layer distillation at about125 C./ 0.05 mm. Hg, a clear, yellow liquid containing about 10.25% ofNCO-groups is obtained.

Although the invention is described in considerable detail in theforegoing examples, it is to be understood that such examples are solelyfor purposes of illustration and that many variations may be made bythose skilled in the art without departing from the spirit and scope ofthe invention.

What is claimed is:

1. Mixtures comprising:

(a) about one mol of 5-si1aimidazo1idones-(2) which contain isocyanategroups having the formula:

wherein R and R are the same or diiferent and are C -C alkyl radicalsand C -C alkoxy radicals which may be haloor cyano substituted, or R andR together represent a bis-hydroxyalkylene group containing 1 to 3carbon atoms;

R is a hydrogen atom, an aliphatic or cycloaliphatic hydrocarbon radicalcontaining up to 15 carbon atoms which may be olefinically unsaturatedor an aryl radical containing up to carbon atoms; and

R is a divalent aliphatic, cycloaliphatic, araliphatic or aromaticradical containing up to carbon atoms which may contain hetero-atomsselected from he 16"- group consisting of oxygen, sulphur, nitrogen andchlorine; with (b) urethanes of the formula R -OCONH-R -(NCO) wherein mis 0 and 1;

R is a C to C alkyl radical; and

R is a radical R when m=1 and said urethane is present in an amount upto 1 mol, and when m=0 said urethane is present in an amount up to about10 mols with the proviso that each one of the components amount to morethan zero mols, R is a radical of the general formula:

wherein R R R and R are as defined hereinabove.

2. A process for the preparation of the mixtures of claim 1 wherein anaminomethyl alkoxysilane of the formula:

m-sn-cm-mr-m References Cited DOS 1,954,447, Noll et a1., June 5, 1971.Available on Reel A498/499, Patent Oflice Search Center.

DONALD E. CZAJA, Primary Examiner H. S. COCKERAM, Assistant Examiner US.Cl. X.R.

161190, 206, 213; 252-182, 189; 260- NC, 448.2 W

UNITED STATES PATENT OFFICE CERTIFICATE OF CJQRECTIUN Patent No.3%}195Q253 Dated February 19.; 19.74

Inventoflg) Bernd Quiring et al. Page 1 E 5 It is certified that errorappears in the above-identified patent and that said Letters Patent arehereby corrected as shown below:

In the heading to the printed specification, line 5, after "Leverkusen,"insert Hans Dietrich Golitz, deceased,

late of Cologne, Germany, by Ingrid Irene Klarchen Golitz, heiressUNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3I793,2S3 Dated February 19 1974 lnventofls) Bernd Quiring et al Page 2of 5 It is certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

Column 4, line 65 "precess" should read process Column 7 line 73,"rnigs" should read rings Column 10 line 44 "1:0 .0410 8" should read1:0 .04:0 8

Column ll line 73 between the two formulae insert and Column 14 line 74,after "85 C insert to about 90 C.

Column 4 line 16 formula II should appear as shown below:

Formula III for that portion of the formula reading C NCO should read -R-NCO Column 5 all the formula under the portion entitled"5-silaimidazolidones- (2) that portion of the first formula reading CHCH \S/ ""\N I C should read UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 22 253 Dated February 1974 P 5 lnventor(s) BerndQulrlng et a1 age 3 of It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

the portion of the second, third, fourth and fifth formulae reading Sshould read Si Column 6, the second formula under that portion entitled"Prepared from-" reading ?C3H should read (IJC H Column 7, the thirdformula under the portion entitled "5-silamidazolidones-(2)" reading OCH0 CH Si /Si Column 8, the fifth formula under that portion entitled"Prepared from" reading UNITED STATES PATENT OFFICE CERTIFICATE OFCORRECTION Patent No. 3 @1795 D d ry 1 19 74 B d lnventor( em Qu1r1ng eta1 Page 4 of 5 It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

, Z NCO NCO should read CH 3 CH CH CH Column 10 Example 2 line 5 thatportion of the fi f l Weading I I i should read (CH NCD v [CH --NCOColumn 14, Example 12, line 10, that portion of the fomnula reading H C-CO I H C O CO UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIUNPatent 3,793,253 Dated February 19, 1974 lnventofls) Bernd Qulring etal. Page 5 of 5 It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 5, the formula under the portion entitled 5 silaimidazolidones(21" that portion of the third formula reading P Q should read Signedand Scaled this Fifth Day of October 1976 [SEAL] v Arrest:

RUTl-l C. MASON C. MARSHALL D'ANN Arresting Officer CommissionerofPatents and Trademarks

